酸性矿坑排水对流域水体和土壤的影响

酸性矿坑排水对流域水体和土壤的影响

1管理社会相关的文献母区划。喜报血。第四组血容量（amd）的ph值低于3.5，这是喜过式生态能力的强化部分。Coalsandwastescontainingpyrite(FeS2)andmineralsassociatedwitharsenicareexposedtooxygenandwaterduringandaftercoalminingoperations,andcontinuetooxidizeandhydrolyze,whichproducetheAMD.AMDhasfreeacidityandcontainssolublemetalsandmetalloids,whicharetoxictoaquaticlife,wildlifeandvegetation.Acidificationofsoilcancausedamagetothefinerootsofplantsandlossofnutrientswhichmayinterfereordestroythesoilmicrobialcommunitiesrequiredforhealthyplantgrowthandmaintenance,andincreasesmetalbioavailability.EgieborandOnigaveadetailedreviewofthecurrentstateofscientificknowledgewithregardtothemagnitudeoftheproblem,thechemistryandmechanismofsulfidemineraloxidationandacidrockdrainage(ARD)formation,theroleofmicroorganismsinARDformationprocess,andtheproposedapproachesforthetreatment,control,andpreventionofARDformation.BecausethecarbonaterockshavethecapacitytoincreasepHvaluesandreducethecontentsofseveraldissolvedmetals,itisimportanttoknowtheeffectsofAMDonwatersandsoilinakarstdominatedbasin.Findingsandinterpretationsforalmostthreedecadesofresearchhavebeencontroversial;amoreobjectiveviewisnowpossibleinthelightofrecentresearchandassessment.Itisimportanttojudgethedegreeandextentofacidification,andtheneedandeffectivenessofitscontrol.BasedonalongtermrecordsofanetworkoflargestreamsdegradedbyacidminedrainageinthenorthernAppalachianhighsulfurcoalregion,Koryaketal.foundthatalloftheAlleghenyRiverdrainagebasinstationshavedemonstratedsteadyandsubstantialdeclinesinacidityandassociatedincreasesinpHandalkalinityoverthepastthreedecades,andoxidativeexhaustionofpyriticmineralsexposedbyminingisproposedasamajorfactorinfluencingthesetrends.InordertoshowtheimpactofAMDtothewaterbodiesandsoilsinabasinscale,atypicalhighAscoalmineinXinren,Guizhouwaschosenforthisstudy.Thepurposesofthisstudyare:(1)toshowthedistributionofpHandECinsurfacewatersandsoil;(2)todetermineacidificationinthebasinsystem;and(3)todiscussprocessesofAMDeffectsonsoilandwater.2u2004范围LocatedattheSWofGuizhou,alow-latitudeplateauinChina,theXingrenCountyhasamoderatesubtropicalhumidmonsoonclimate,withanannualaveragetemperatureof15.2℃andannualaverageprecipitationof1320.5mm.TherainyseasonisfromMaytoOctober,inwhich84.5%oftheannualprecipitationisavailable.Thestudyareaisatypicalkarstareawithdepressions,hoodoosandsoon.Thebedrockismainlycomposedofsedimentarycarbonaterockssuchaskarstifiedgraydolomites,dolomiticlimestonesandgraylimestones,sometimeswiththeoccurrenceofmarlsandclaysfromthePermian-Triassicperiod.XingrenCountyiswellknownforcoalandothermineralresources.Thecoalreserveswasestimatedtobemorethan45billionton.Thedevelopmentofcoalindustryenhancestheeconomicdevelopment,howevertheAMDbecameaseriousproblemtotheecologicalsysteminthearea.Thewastewatersfromcoalminingtypicallycontainhighlevelsofmetalions,suchasiron,copper,aluminum,andmanganese,aswellasmetalloidsofwhicharsenicisgenerallyofgreatestconcern.Thestudyareaisoneofthehigh-arseniccoalminingareasinXingrenwith4coalstratacontaininghighAscontent.ThecontentofAswasfoundintherangefrom100mg/kgto3.5×104mg/kg,andthehighestwasupto(3.2~3.5)×104mg/kg,muchhigherthanitsaveragecontentinChinaandtheworld(7.79mg/kgand5.0mg/kgrespectively).Thehigh-arseniccoalismainlyhostedinthePermianLongtanFormationandintheanthracite.Therealsohavesomegoldmineraldepositnearbythehigh-arseniccoal.Fig.1isamapofstudyarea.Therearetworeservoirs,theMaoshitouReservoirandtheShitouzhaiReservoirwiththecatchmentareasof1.66km2and1.17km2,respectively.Bothreservoirshavebeenbuiltforseveraldecadesandarestillusedforirrigation.IntheupstreamoftheMaoshitouReservoir,small-scaleminingofunknownproductionquantitiesoccurredfrom1990stotheearlyof2000s.Severalsmallsulfidicwaste-rockpilesarestillremainedinthearea.Thelodesoccurinsteepcountry,withslopeslocallyupto30°andataltitudesbetween1580and1630metersabovesealevel.Intheminedareas,wastematerialsweredumpedonsteepslopesresultinginmassesofunconsolidatedminewastesextendingdownslope.Coalminingwastesarecomposedofdiversematerialsrangingfromsiltyparticlesof<1mmtoboulders0.5mindiameters.Constituentsincludemetasedimentarymaterialaswellasminorsulfidefragments,pre-andpost-mineoxidationminerals,andassortedminingwaste.Uncontrolledsulfidicmaterialallowscontinuousoxidationofthewaste.Littlevegetationexistsonthewastedumps,andgulliesdrainingtheminesitearedevoidofvegetation.DrainagefromtheminesiterunsintotheMaoshitouReservoirabout500mdownstreamfromthepitheads.Duringdryperiods,drainageminedumpappearstobetheonlysourceofsurfacewatertothereservoir.ItwasfoundthatwaterintheMaoshitouReservoirwasaffectedbyAMDfromtheupstream,butwaterintheShitouzhaiReservoirwasinitsnaturalcondition.Riceproductionisthemostimportantagriculturalactivityandthepaddyfieldsareirrigatedbythewaterfromreservoirs.Whentheriverflowsdown,itdisappearsatR40andreappearsatR41,whereisbelievedthatthereexistsasubterraneanriverinthestudyarea.3关于solectedinpolusgraftingsiphinvilrasFig.1showsthedistributionofsoilandwatersamplingpointsforthisstudyarea.DO,pH,ECandtemperatureofsurfacewaterincludingAMD,riverandreservoirsweremeasuredonsitefrom2006to2008byusingportablepHmeter,ECmeterandDOmeter(Multi-meters340i,Germany).Allofthewatersampleswerefilteredthrough0.45μmfiltersbeforecollectedinpolyethylenebottles.Sampleswerestoredinarefrigeratorat4℃atthelaboratorybeforeanalysis.Majoranionsandcationsweremeasuredbyionchromatography(IC,ICS-90,DionexCorp.,Sunnyvale,CA,USA)andAtomicspectrophotometer(USA),respectively.Soilsamplesweretakenat39pointsinthepaddyfieldsdownstreamofthereservoirstostudythepHdistributionoftopsoils(Fig.1).Additionally,a100cmdeeppitwasdugatS01andsoilsweresampledat10,20,30,40,50,60,70,80,90and100cmindepth.Foreachsoilsample,25mLdistilledwaterwastakenintothebottlewith10gsoilsampleinit.ThebottlewasshakenforminutesbeforethepHvaluesofsoilweremeasuredbyportablepHmeter.Also,theinformationsuchaswateruse,riceproduction,landuseandsoonwasgottenbyinterviewingtothelocalpeople.4产品系统4.1通过转色行为获取reelvificipar,u2004,3.,5.,4.,4.,5.,4.,5.,4.,5.,5.,4.,4.,5.,7.,3.,5.,4.,3.,5.,7.,7.,4.,7.,3.,5.,5.,5.,5.,5.,7.,4.,5.,5.,7.,5.,5.,5.,7.,7.4.3.3.3.,5.,5.,7.,7.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.4和4-dr在meTheAMDexistsinseveralminingpitsanddrainstothereservoirsdownstream.ThesurfacewatersintheupstreamoftheMaoshitouReservoirwereconsideredasAMDbecauseofdifficultytoidentifytheallsourcesdischargingtothereservoir.ThepHvaluesofAMD(Tab.1)rangedfrom1.93to4.01withanaverageoflessthan3.TheaverageECwas2526μm/cmrangingfrom550to7240μm/cm.TheaverageofDOintheAMDwas5.09mg/L,littlehigherthanthatintheMaoshitouReservoir.Whereacidminedrainagewatersfromthedumpinthemineareaenteredthereservoir,theaquaticandbacksideplantcommunitiesdisappeared.Moreover,therewereabundantFe-richyellow-browngelatinousprecipitatescoatingtheriverbedorthebottomofthereservoirandfloatinginreservoir,andmineral-saltencrustationsontheriverbankandbed.4.2主要参数估计AsshowninTab.1,waterintheShitouzhaiReservoirwasneutralandtheECandDOvalueswere99μm/cmand5.81mg/L,respectively.However,becauseoftheimpactfromdumpinthemineareathepHvalueintheMaoshitouReservoirdecreasedsharplytoanaveragevalueof3.09andtheECvaluejumpedupto1275μm/cm.ThepHandECintheMaoshitouReseveroirrangedfrom2.72to3.51andfrom591to1996μm/cm,respectively.TheaverageDOvalueintheMaoshitouReservoirwasalsolessthanthatintheShitouzhaiReservoir.BecauseofthelowpH,noaquaticlifecouldbefoundinthereservoir.TheAMDalsohadstrongimpactontheaquaticecosystemintheriverdownstreamofthereservoir.4.3indexrafterrace-pcrsiph/atr3.8kmupst东北部roxraft/atrace净化inter联合保护/投资index/atraceract/atracerat5.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.4.3.3.3.3.3.4.3.3.4.3.4和3.4.3.4.3.4.3.4.3.4.3.4.3.3.3.4.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.4和5.8运用phratchenratchenratchenratchenratchThepH,ECandDOvaluesinriversnotaffectedbyacidicwaterrangedfrom6.06to7.98,31to248μm/cm,and6.47to7.01mg/L,respectively.Fig.2showsthevariationsofEC,DOandpHalongtheriverfromtheMaoshidouReservoir,respectively.Forconvenience,theR04watersamplingpointattheheadofMaoshidouReservoirwassetasthestartingpointfromwhichtheacidwaterfloweddowntothebasin.Whenitrunsthroughthebasin,pHchangedlittleuntil3.8kmdownstreamfromthereservoir.Intheintervalbetween3.8kmto5km,itbecameasubterraneanriver.ThepHvalueincreasedto4.4whenitflowedoutatpointof5kmdownstreamfromthereservoir.Ontheotherhand,ECofriverwaterdecreasedfrom1268μm/cmattheoutletofMaoshitouReservoirto953μm/cmatR40.Furthermore,ECvalueofwaterbecame563μm/cmattheoutletofsubterraneanriveratR41.Intheopenchannelcondition,theDOvaluedecreasedfrom10.9to9.0mg/LbeforeitdisappearedatR40.Whenitflowedintheclosedchannelasasubterraneanriver,DOvaluesdecreasedto6.2mg/LattheinletofR41.TheDOvaluerecoveredto8.5mg/LatR42becauseofaerationintheopenchannel.Throughawholeyear,sulfideoxidationandmineral-dissolutionprocessesgeneratedacidminedrainagewatersthatmightenterlocalsurfacewatersandaquifers.ChangingredoxconditionscommonlyledtotheformationofFe-richprecipitatesontheriverbanksandbed.Thesevisibleeffectsofacidminedrainagepollutioncontinuedfor5kmdownstreamwherethestreamprogressivelyrecoveredtoexhibitalittletypicalaquaticecosystemwithdiverseplantspecies.4.4清苏霍姆性别清cq补—SoilOvertime,soilsirrigatedbyacidicwaterbecomeprogressivelymoreacidasaresultoftheseprocessesanddevelopastrongdepthgradientfromthesurface,throughtomineralhorizons,downtotheunweatheredmaterialoftheparentbedrock.Thetransitionlayers,ordepthhorizons,havedifferentchemicalcharacteristicsandresponsestoacidicwaterinputorthethroughflowofsoilwater.Atpresent,thepHofsoilintheareaunaffectedbyAMDwasabove5.5averagely.Fig.3showstheverticaldistributionofpHinsoilofpaddyfieldirrigatedbylowpHriverwateratS01,wherericeproductionwasverylowaccordingtotheinterviewoflocalpeople.ItwasfoundthatthepHvaluesofsoilfromthesurfaceto90cmindepthwerelessthan3.9withanaverageof3.7,whichwasmuchlowerthanthatinthenaturalcondition.Itwasbelievedthatthebuffercapacityofsoiltoacidicirrigationwatervariedwithdepths.ThelowestpHvaluewasaround3.3inthelayerof70to80cmindepthfromthesurface.5子阶段5.1rectityofficicipacisiph+erincipacisiph+authoperationreacityrectityrectitysoftings和第三部分关于“rectity”的表达,4.4.4.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.4.3.4.3.4.3.3.4.3.3.4.3.4.3.4.3.4.3.4.3.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.3.3.4.3.4.3.4.3.4.3.3.4.3.4.3.4.3.3.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4.3.4和5.5.5.5.4.TherearetwomajorprocessestoregulatethepHvalueofsurfacewaterinthestudyarea.Oneisthedilutionbythedischargeofgroundwateralongthechannelortheinflowfromotherunpollutedriver.Theotheristhechemicalreactionbetweentheacidicriverwaterandrockorsedimentsattheriverbed.AMDisusuallycharaterizedbyitslowpH,highECandhighconcentrationofSO2−442-ionastheresultofsulfideoxidationinthemineoritsdump.Inthestudyarea,sulfidesweremainlypyriteandthefollowingreactionwilloccurwhenoxygenorFe3+areavailable.Theoverallreactioncanbewrittenas:FeS2+14Fe3++8H2O→15Fe2++2SO2−442-+16H+Fe3+isthepredominantoxidantatlowpHandisusuallythelimitingreagent.Theinorganicoxidationrateofferrousion(Fe2+)belowpH3isslow.Acidophilicorganisms,however,cangenerateenergybyconvertingferrousirontoferriciron.Asaresult,thewaterfromthecoalminebecameacidicbecauseoftheincreaseoffreeH+ion.Extensivedistributionsofdolomites,dolomiticlimestonesandgraylimestonescanbefoundintheriverbed.Whenacidicwaterflowedintotheriver,thereactiondescribedabovehasgeneratedH2SO4andfreeH+ionforcarbonatesolutionatthebanksandbedsoftheriver.Balancesweredelicateinsuchsystemandtheproportionsofreactantswerevariedandreplacementornetprecipitationoccurredattheriverbed.Itwasfoundgypsumintheformofthincoatsatthesurfaceofgrassleavesortherockblocksalongtheriverbanks.IncontactwithAMD,thelimestoneofriverbeddissolves,producingcarbonatealkalinitywithincreasesinpH.However,theformationofferricoxyhydroxidesinthereactioncoatlimestoneandresultinoxidizingenvironmentsandeliminationofanyfurtherneutralizingcapacity.Thetypicalreactionsinvolvedinriverbedneutralizationofacidmineeffluentare:CaCO3(s)+SO2−442-+2H+→CaSO4(s)+H2O+CO2CaCO3(s)+2H+→Ca2++H2O+CO2Also,otherreactionscanbefoundasthefollowing:CaCO3(s)+SO2−442-+2H++H2O→CaSO4·2H2O(s)+CO23CaCO3(s)+Fe3++3H+→3Ca2++Fe(OH)3(s)+3CO2ItwastoldthatthewateratpHof3.0willdissolve50%moreCaCO3thanthenaturalonetoreactwiththebarerockattheriverbed.Infact,thereweremanycaveswithintheblocksandmostofCaCO3componenthasdisappearedduringthechemicalreactionwhenacidicwaterflowedover.Asaresult,therockblocksattheriverbedinthestudyareaweresobrittlethattheywerebrokenintopiecesjustpushingwithfingers.Ontheotherhand,depositionofsuspendedmatterfromtherivercanhaveasignificanteffectonhyporheicexchangeandadverselyimpactonthebenthicandaquaticecosystems.Itwasfoundthattheyellowsuspendedmattersbroughtbytheacidicwatercoveredtheriverbedinthethicknessofafewmillimeterstoonecentimeterwhenitflowedover.FinecolloidalparticleswiththepHlessthan4.0carriedalargepollutantloadinthecontaminatedriver.Inaddition,depositionoffinesintoriverbedsreducedgreatlyhyporheicexchange,whichpreventedtheacidicriverwaterreactfurtherwithlimestoneofriverbed.Asaresult,pHofriverwaterwaslowevenitflowedacrossthestudyarea.Thereweretwochemicaltypes,Ca2+-HCO-3andCa2+-SO2-4inthesurfacewaterofstudyarea(Tab.1).Theformerwasthewaterwithouteffectsofacidicwater,andthelatterwasfoundintheAMD,theMaoshitouRiverandtheriverwithpHvaluebelow5.0.Also,ItcanbeconsideredthatCa2+wasthedominatecationinthesurfacewaters,butthedominateanionwasSO2−442-orHCO-3,dependingonthewaterwithorwithouteffectsofAMD.Fig.4showstherelationshipbetweenECandSO2−442-concentrationinwatersofstudyarea.ItwasfoundthattheconcentrationofSO2−442-increasedwithEC.Astheacidicwaterfloweddownfromthepitheadsofcoalmine,ECvaluedecreasedcontinuallywiththedecreaseofSO2-4concentrationalongtheriver.Whenthewaterflowedalongthesubterreanriverinthestudyarea,DOdecreasedsharply(Fig.2).Itinhibitedoxygenpenetrationandpreventedtheoxidationofferrousironintheacidicwater.Asaresult,thepHofwaterrecoveredmorequicklythanthatintheopenchannel.5.2u2004范围/soel-sit-sit-sit-sit-sit.国际习惯法第20条第3和3.Soilsareprincipallytheproductofthebreakdownbyweatheringofgeologicalmaterials,eitherthebedrockorthedriftmaterialsbroughtfromamoredistantlocation.Otherconstituentscomefromthedecayofplantandanimalmaterialsintheuppersoilhorizons.Innaturalcondition,thedegreetowhichsoilacidityisneutralizeddependsonthebasereserve,whichinturnisdependentontherateofweatheringofgeologicalmaterials.Thegenerationandreserveofaciditywithinsoilsgreatlyexceedsthatdepositedinrain,althoughincreasingacidificationofsoilshasoccurredoverthelast100years.However,thesoilsarechanginggreatlyinareassubjecttoAMDwaters,whichismainlycontrolledbyphysical(andhydrological)andchemicalprocesseswithlimitedbiologicalactivityinthesoil.Land-usepracticesinfluencetheacidificationofsoils;theuseofacidwaterforirrigationleadstoenhancedacidification.Farfromtheindustrializedregion,thepHofrainwaterisexpectedbetween5.6and6.4inthestudyarea.InthedownstreamoftheMaoshitouReservoir,thereweremanypaddyfieldsirrigatedwiththecontaminatedacidwaterbylocalpeople.Fig.5showsthefrequencydistributionsofpHvaluesforthewatersofAMDandtheMaoshitouReservoir,aswellasthetopsoilswithandwithouteffectsofacidicirrigationwater.AllhadthenormaldistributionsfortheirpH.ItwasfoundthattheexpectedvalueofpHwas3.0fortheAMDandacidicwaterreservoir.However,themostfrequencyofpHvaluesinthesoilwithandwithoutacidicwaterirrigationwere5.0and6.5,respectively.AccordingtotheclimatologicallycharacteristicsinGuizhouprovince,itcanbeestimatedthatevaporationwillbe800mm/yearinthestudyarea.Asaresult,thereshouldbemaximally8.64×105m3ofacidwaterwithitspHaround3flowingoutfromtheMaoshitouReservoir,partofwhichwasusedforirrigationforadecade.Acidsintheirrigationwateralsocontributedtotheweatheringprocess.Thereleaseofbasecationswasneutralizing,i.e.,theyconsumedthehydrogenions—thelowerthepHoftheirrigationwater,thegreaterthereleaseofcations.OrganicmaterialandpHdecreasedwithdepth,whichcausedweatheredcationstoredistributebetweenthesoilexchangesitesandtheinfiltratingwater.Inthestudyarea,sulfatefromacidicirrigationwaterinputtosoilsandcausedananionshiftinsoildrainagefromacompositiondominatedbyHCO-3andorganicanionstoonedominatedbySO2−442-.TheincreaseinSO2−442-wasgreateronanequivalentbasisthanthedecreaseincarbonateandorganicanions,raisingtheionicstrengthofthesoilsolution.Soilswithasufficientsupplyofbasecationsfromweatheringcanabsorbandneutralizetheaciditygeneratedwithinthesoilsandfromacidirrigationwaterwithoutacidification,butwhenacidinputswereinexcessofthiscapacity,thesoilbecomesincreasinglyacidic.6aciditysofterityofficicipa回/回采sindthince,krafterization,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,krafts,kra